wireproto: allow unbundle with hashed heads parameter (issue2126)...
wireproto: allow unbundle with hashed heads parameter (issue2126)
Current wire protocol of unbundle sends the list of all heads in the remote
repository to avoid race condition. This causes "URL too long" error on HTTP
server when the repository has many heads.
This change allows clients to send SHA1 hash of sorted head hashes instead.
Also, this introduces "unbundlehash" capability to inform them that the server
accepts hashed heads parameter.